RNA: Structure, Biophysics and Physiology

National Heart, Lung, And Blood Institute

Investigators

Linked publications, trials & patents

Abstract

In the past year, we made important advances in the study of cellular ribonucleoproteins and the eukaryotic stress response. We characterized through cryogenic sample electron microscopy (cryoEM,. cryo-EM) and single-molecule and bulk biochemistry the DEAH-box helicase DHX36. This essential protein is involved in key regulatory processes, and, accordingly, its dysregulation is connected to both cancer and vascular disease. Uniquely among known DEAH-box proteins, DHX36 has the ability to resolve both, DNA and RNA substrates. Our structural analysis revealed the molecular basis for this versatility. Moreover, our high-resolution structures and structure-based analyses explain how this helicase achieves specificity for its substrate G-quadruplex nucleic acids without resorting to direct sequence readout. Atomistic understanding of this helicase opens the way to the discovery of small-molecule inhibitors that may provide new therapeutic avenues of intervention in cardiovascular disease. We also published a first report of investigations into the eukaryotic stress response that have been taking place in our group for the past decade. Stress granules are a key cellular response to extracellular stressors, and the ability to cells to make these cytoplasmic condensates has been shown to be protective in disease states ranging from ischemia and cancer (where the stress is hypoxia) to metabolic syndrome and diabetes (nutrient deprivation) to proteostasis (neurodegeneration). We reported the first biochemical purification of stress granules that does not rely on candidate protein approaches. This unbiased preparation revealed that stress granules are comprised of discrete particles with complex protein and RNA composition. Critically our analysis shows both biophysically and cell biologically that stress granules are heterogeneous. This demonstration of the particulate and heterogeneous nature of stress granules has important implications in the development of future interventions into both acute and chronic medical conditions.